Darwin's Theory of Evolution and Evidence for Change

Natural Selection

The process by which individuals with advantageous traits survive and reproduce at higher rates.

Variation

Differences in traits arise from mutations, genetic recombination, and environmental factors.

Natural Selection

The process by which individuals with advantageous traits survive and reproduce at higher rates.

Variation

Differences in traits arise from mutations, genetic recombination, and environmental factors.

Overproduction of Offspring

More organisms are produced than can survive, leading to competition.

Differential Reproductive Success

Those with favorable traits pass them on to the next generation.

Fossil Record

Shows transitional species and changes over time.

Biogeography

Species in similar environments evolve similarly (convergent evolution).

Homologous structures

Structures that share ancestry but have different functions.

Analogous structures

Structures that have different ancestries but similar functions.

Embryology

Similar embryonic development suggests common ancestry.

Molecular Biology

DNA and protein similarities indicate evolutionary relationships.

Gene Pool

The total genetic material in a population.

Hardy-Weinberg Equilibrium

A model where allele frequencies remain constant (requires no mutation, random mating, no gene flow, large population, and no selection).

Hardy-Weinberg Equation

p² + 2pq + q² = 1 (genotype frequencies) and p + q = 1 (allele frequencies).

Directional Selection

One extreme trait is favored.

Stabilizing Selection

Intermediate traits are favored.

Disruptive Selection

Both extremes are favored over the middle.

Sexual Selection

Traits that enhance mating success increase in frequency.

Allopatric Speciation

Physical barriers separate populations.

Sympatric Speciation

No physical barrier, but reproductive isolation occurs.

Adaptive Radiation

One species diversifies into multiple species due to new niches.

Phylogenetic Trees

Show evolutionary relationships.

Cladograms

Use shared characteristics to show ancestry.

Outgroups

Serve as a reference to distinguish evolutionary traits.

Mass Extinctions

Large-scale species loss that alters ecosystems.

Genetic Drift

Random changes in allele frequencies (founder effect & bottleneck effect).

Gene Flow

Movement of alleles between populations.